Heat exchange unit



Peb. 5, 1935. R. MAUTSCH 1,989,996

I HEAT EXCHANGE UNIT Filed Jan. 5, 1952 y 'lll/I Patented Feb. 5, 1935UNITED STATES- remates PATE NT` OFFICE HEAT EXCHANGE UNIT RobertMaatsch, Brussels, Belgium, assigner tg Manufacture GeneraleMetallurgique, Societe Anonyme, Brussels, Belgium, a company of BelgiumApplication Jan s, 1932, serial? No. 584,866

In Belgium February 26, 1931 5 Claims. (01.'25'1-248) made of cast ironor of an alloy of aluminium,

for example, Whilst the tubes are of copper or other metal having a lowresistance to the iiow of heat and good `anticorroding properties, but

` being unsuitable for casting or of prohibitive cost.

For many purposes it would however be desirable l that the headers, orat least those portions thereof which come into contact with the iiuid.flowing through the apparatus, be made of the same metal as the tubes,or of some metal possessing properties considered requisite for theeiiicient operation of the apparatus.v By this means it would bepo'ssible to obviate oxidization or corrosion of the f headers and theeffect thereof upon the 'uid flow'- ing-through the heat-exchangeapparatus, as well as to preclude certain electrolyticaL phenomenaliable to cause serious damage, due to theformation of electric cells atthe points where tubes and headers consisting of different metals arejoined together, and to the presence of a liquid in thel apparatus.

The present invention supplies simple means for attaining this endwithout increasing the cost ofthe heat exchange units appreciably, byproviding a header-box whereof the walls consist'of thin sheets of themetahselected for use', said headerbox being strengthened by means of ametallic outer jacket or casing which may be continuous and enclose -thesheet metal header-box completely, or be formed to enclose only certainportions of the same, the joints for example, the remainder ofthe-header-box being left bareif it is Inot intended to withstand highpressures. Preferably, the header box itself is u sed as a casting core,and the metal of the j acket or casing is cast directly around the same.

Many known means are available, such as threaded nipples, soldering,welding, expanding .and the like, for securing tubes to headers. It isvoften difhcult however to obtain by any of these l means joints adaptedto remain iiuidtight at high pressures and, according to the invention',the ends 'of said tubes are therefore preferably exp,-

' iron casing.'

bedded in and rendered integral with the metal of the casing surrounding.the header, when' said ca sing is cast. For this purpose, the tubes arejoined tothe header-box, said header-box is `placed in the casting mouldto act as a casting -core therein, and metal is then cast into saidmould around the ends of the tubes at the same time asv it is castaround the header-box or those portions thereof which it is desiredtovstrengthen. 4The tube-ends anchored within the header-box may besmooth, may be provided with a ring shrunk thereon, or may be corrugatedand beA provided with said shrunkring or not, butlthey are preferablystrengthened to withstand the" v shrinkage stressesof the metal cast toform the casing, by being provided with an inner liner. Said tube endsare preferably fitted into openings inthe header-box previous tocasting, and

plain or threaded nipples fitted into openings -in the header-box in thelike manner likewise become embedded in the metal, when the same is castto form a casing or jacket.

In order that the invention may be clearly understood and readilycarried into effect, the same will nowbe described more fully withreference to the accompanying drawing which il1ustrates,'by way ofexample, a few constructional embodiments thereof and -in which:

liig. 1 is a horizontal section of a header-box and of the separatemembers to be assembled therewith, before casting, A

. Fig. 2 shows, likewise in horizontal section, the' same membersassembled with the header-box and embedded,v together Figs. 3 to 6 showmodifications of the invention. In all of the figures, 1 indicates thethin metallic header-box, to which the tubes 2 of the heat ex- 'changeapparatus are secured by expansion or' by other suitable means, and 3'indicates themetal casing cast around said header-box 1 which is used asa casting core, and around the ends vof tubes 2. An internally threadednipple 4, expanded or otherwise secured in header-box 1, is likewiseembedded in the metal of casing 3 by the casting thereof.

In the constructional embodiment shown in Fig, 2, the ends of tubes2'are smooth, devoid of vany reinforcement, andare gripped in the metalof casing 3 solely by the pressure of said metal due to lthe shrinkagethereof after casting. When said tubes are thin, as is usually the case,their ends are preferably reinforced by means of an inner liner 5 (Fig.3) adapted to prevent the collapse ofthe side wall of said tubes underthe with the same, in a cast f pressure set up by the shrinkage of thecast metal, and thus to assist in providing a solid' The strength ofanchorage for the tube ends. said anchorage may further be enhanced byshrinking upon the tube ends a ring of comparatively large diameter 6(Fig. 4,) adapted to resist still better the shrinkage stresses of'casting 3 and to provide a joint'the tightness of, which is all thegreater that said stresses act upon' a large diameter. Should the metalof said casing not l surround the tube in a perfectly iluidtight mannerand some of the fluid 'contained inthe header therefore coze along tube2,'ring6 will force said uid to follow a path so circuitous esito -bealone suiiicient, in most cases, to arrest said oozing.

Instead of being smooth, the end of tube 2 may be ..roughened, threadedor corrugated as at *I (Fig. 5), to afford the cast metal of the casinga better grip upon said tube and likewise to 'force any fluid oozingalong lsaid tube to travel a cir--l cuitous path.

The greatest possible degree of resistance to mechanical stresses and ajoint adapted to remain tight irrespective of the pressure of the fluidwithin the header and tube, may be obtained by providing within thecorrugated tube end a smooth or corrugated strengthening-liner 5a (Fig.6), and by shrinking an outer ring 6a upon said tube end between two ofsaid corrugations 7.

reinforced or made tight. This modiiication may be met, according tocircumstances, by a suitable arrangement of the mould.

The invention is not however limited to the use of a cast jacket orcasing and in certaincases this member may, be formed merely of a Jacketme chanically cold fitted or hot shrunk around header-box 1, tubes 2'andnipples 4 being then assembled with said header-box in a'uid tightmanner, by being expanded or soldered therein, for example. Neither isthe invention restricted to any of the further constructional detailshereinbefore described, which might be modied Widely without departurefrom its scope, said invention beingv limited'only by its essentialfeatures as set forth Yin the appended claims.

I claim: 1. In a heat exchange unit, the combination of an aperturedheader member formed `of sheet metal of high thermal conductivity, witha plurality of tubes having lateral projections. formed at the endsthereof, said tubes being formed of a j metal analogous to that of saidheader member and being each secured by one end in one of saidapertures, a pressure resisting liner within each said Atube end, and anouter stress-resisting casing of cast metal around said header memberand said tube ends, and rigidly gripping said projections on said tubeends.

2. In combination in a heat exchange unit, anapertured header 'memberformed of sheet metal, a plurality of tubes each secured by one endwithin said header member through one of said apertures. a connectionnipple secured within said header member through one'l of saidapertures, a ring of comparatively large ,diameter shrunk outwardly uponeach of said tube ends' and a casing of cast metal extending'around inimmediate contact with said header member,

- tube ends, shrunk rings 'and conne'ction nipple,

to hold the same in uidtight relationship -for the purpose setl forth. Y

.3. In combination in a heat exchange unit, an

apertured header member formed of-heat con-` l ducting sheet metal, aplurality of' tubes formed of an analogous metal and each anchored byone end within said header member through one of said apertures, athreaded connection nipple anchored within :saidheader member throughanother of said apertures, a pressure-resisting liner-inserted in eachsaid tube end, lateral projections upon each said tube end 'formedoutward- .ly'of the periphery thereof, a ring'` of comparatively largediameter shrunkupon said lateral projections of said tube ends, and ametal casting formed in contact with and around said assembled headermember, tube-ends, nipple, liners, projections and rings and enclosingand gripping the same.

4. In combination in a heat exchange unit, an aperturedhhead'er memberformed of thin heatconducting metal, a plurality of tubes formed Vof acognate-metal and each secured by one end within, said header memberthrough one of said apertures, a threaded connection nipple securedwithin said header member through another of said apertures, astiifening liner'within each said tube end, lateral projections formedoutwardly of said tube ends, a large-diameter ring shrunkoutwardly uponeach said tube end, and a metal jacket fashioned and secured around andin contact with said header member, tube ends, nipple,

projections and rings, said jacket enclosing and gripping the same influidtight relationship.v

5. A jointed, two-part heat exchange device. consisting of means for thealmost instantaneous exchange of heat between the device and the-fluidto be acted upon while avoiding electrolytic action at the joint betweenthe said two-parts and the occurrence of detrimental oxides, at the sametime imparting sumcient strength to the device to withstand the highmechanical vstresses normally encountered in heat exchange use whileenabling th'e maintenance of first-cost at a; minimum, the said meanscomprising a complete boxshaped header member, comprising one of thesaid two-parts, formed of Athin sheet metal of high thermalconductivity, said header being too weak in itself to withstand thestresses prevailing when it is in operation, said header member havingapertures therein. a plurality of tubes 'capable of directly contactingwith and entering into intimate heat .exchange relation with the iluidto be acted upon. and formedpof the same metal as the header, andcomprising the other of the said two parts, jointed to the first part,said tubes being sufliciently thinto enter into almostinstantaneous-heatexchange with said fluid, said tubes each having -oneend 'engaged in anaperturebf said header member, and an 'l outer casing strong enough tovresist the mechanical stresses which prevail, and formed oi aninexpensive metal'cast in substantially iiuidtight manner about only theends of. said'tubes and about the ioint between the ends of the tubesandthe Aadjacent poi-tions of said sheet metal header member, and atleast partly surrounding the-remaining portions of said header member,said tubes projecting outwardly'from said-casing.

. ROBERT MAUTSCH.

